As early as Monday, the US supreme court is expected to rule in Whole Woman’s Health v Hellerstedt, the most significant abortion rights case to come before the justices in more than two decades.

The outcome of this case could have a ripple effect across the country. Although the direct challenge is against a restrictive Texas law, called House Bill 2, dozens of states in the south and midwest have passed almost identical regulations. With the death of Justice Antonin Scalia, it is unlikely that these laws will be upheld in a sweeping fashion. But depending on how Justice Anthony Kennedy votes, clinics across the south could still be forced to close or stop providing abortions.

The case is a dispute over a Texas abortion restriction – one of the nation’s toughest – that requires every clinic in the state to meet expensive, hospital-like building codes and every provider to have staff privileges at a hospital within 30 miles.

The law decimated abortion access in Texas. Before it passed in 2013, Texas had 41 abortion clinics. Today the state is down to 18. If the supreme court allows the law to take full effect, there would be only nine in a state of 5.4 million women of reproductive age.

Supporters of these laws say they are necessary to protect women’s health. Opponents argue that these laws are intended to shut clinics down, noting that the complication rate for abortion hovers around 0.05%-0.2%.

“If you take out a map, you can draw a single line through all the states that are affected by this litigation,” Jennifer Dalven, the director of reproductive rights litigation for the American Civil Liberties Union, said shortly after the court agreed to hear the case.

Here are four possible outcomes.

4-4 SPLIT: Half of Texas clinics close

If Kennedy joins his fellow conservatives – Chief Justice John Roberts, Samuel Alito and Clarence Thomas – for a split decision, it would result almost immediately in the closure of eight of Texas’s 18 abortion clinics. (When the court is divided, the ruling that is being appealed remains in effect. In this case, the fifth circuit court of appeals ruling upheld the admitting privileges mandate and the ambulatory surgery center requirement.)

There wouldn’t be any clinics in the 500-mile swath of Texas between San Antonio and El Paso. With one exception, the only clinics that could remain open are those licensed as ambulatory surgical centers. The exception is a Whole Woman’s Health location in McAllen, which the fifth circuit would allow to operate because it was the only clinic in all of the Rio Grande Vvalley.

A split decision doesn’t set any precedent, which means the impact would be limited to Texas.

5-3 VOTE: Texas law struck down

If Kennedy votes with the court’s four liberals, it could be a victory of historic proportions for abortion rights advocates. All 18 abortion clinics in Texas would be permitted to remain open, and similar laws threatening 13 clinics in six southern states and Wisconsin could be permanently struck down.

But Kennedy has only ever voted to strike down one abortion restriction. It is possible that he would join the court’s four liberals in writing a narrow decision. This decision might strike down HB 2 without setting a sweeping precedent for overturning laws in states beside Texas.

4-3-1 VOTE: Clinics in trouble across the south

Under an obscure and counterintuitive supreme court rule, Kennedy could single-handedly shutter a great number of clinics by siding with liberals in some, but not all of their rulings – a vote of 4 (the liberals) to 3 (the conservatives) to 1.

The outcome for clinics would depend on the points of consensus between Kennedy and the liberals. For example, if Kennedy’s opinion upheld the admitting privileges requirement but not the surgery center requirement, the surgery center requirement would be struck down with five votes – a precedent.

But the admitting privileges requirement would be upheld, and lower courts could be compelled to uphold similar laws. The reason is a semi-obscure supreme court rule which says that when five justices agree on only a few points of law, the “narrowest” of their opinions becomes the opinion of the court. In this case, “narrow” is likely to be interpreted to mean the decision that strikes down the fewest sections of HB 2.

Kennedy could also uphold the surgery center requirement and strike down the admitting privileges requirement.

This is the nightmare scenario for abortion providers in the south and midwest. If admitting privileges laws that the lower courts have blocked are allowed to go into effect, then 11 providers in Alabama, Arkansas, Louisiana, Mississippi, Oklahoma and Wisconsin who have tried and failed to obtain admitting privileges could be forced to close or stop doing abortions.

If Kennedy broke the other way, and upheld surgery center requirements, it could shutter nine of the 18 clinics in Texas and two of Tennessee’s seven abortion clinics.

This scenario comes with all sorts of caveats. Kennedy could support exceptions to these requirements for regions that have only one abortion clinic, for instance, the clinic in McAllen, Texas. The fifth circuit also ruled against an admitting privileges requirement in Mississippi, because it would have closed the only clinic left in the state.

And there are contingencies. The main abortion provider for Hope Medical Group for Women in Shreveport, Louisiana, has admitting privileges. But he has said that he would quit if he is the only abortion provider in all of northern Louisiana.

The court punts: We do this all again

There is speculation that in order to avoid a split decision, the court might remand the case back down to the lower court for further investigation.

During oral arguments, Kennedy asked if it would be “proper” and “helpful” to return the case to the lower court for further investigation into how directly HB 2 was linked to the spate of clinic closures, and to explore whether nine or 10 abortion clinics had the capacity to meet demand for abortion.

Under this scenario, the court would almost certainly allow the Texas clinics to remain open while the case continues.